Continuous process for purifying raw sulfur



P 1, 1954 G. MARULLO EIAL TINUOUS PROCESS FOR PURIF'YING RAW SULFUR CON 2 Sheets-Sheet 1 Filed Feb. 8. 1951 ATTORNEYS INVEWTORS Gerlundo Murullo DohnenicoMorogliano S p 1954 G. MARULLO ETAL 2,689,783

CONTINUOUS PROCESS FOR PURIF'YING RAW SULFUR Filed Feb. 8, 1951 2 -Sheet 2 Fig.

. Mmvroes Gerlcmdo Morullo ATTORNEYS Patented Sept. 21, 1954 UNITED STATES PATENT OFFICE CONTINUOUS PROCESS FOR PURIFYING RAW SULFUR Gerlando Marullo and Domenico Maragliano, Milan, Italy, assignors to Montecatini Societa Generale per IIndustria Mineraria e Chimica Anonima, a corporation of Italy Application February 8, 1951, Serial No. 210,024

Claims priority, application Italy March 28, 1950 1 Claim. (Cl. 23-224) portion, over it whole length, with a, jacket 2,

which extends about as far as the middle line, being provided with joints 3 and 4 for the circulation of the heating fluid. The two heads of the drum I are provided in turn with conduits 5 and 6 respectively for the introduction and discharge of the gas containing S03, and 1 and 8 respectively for the introduction and discharge of the molten sulphur.

The drum I is divided inside into a number bubble in the mass of raw sulphur brought to 10 of chambers by bafiies '9, which in their lower the molten condition. In practice, however, this part extend nearly up to the'height of the middle method ofiers some disadvantages, among which axis, forming an equal number of liquid-proof the following should be specially noted: pockets, while in the upper part (Fig. 2) they are (a) The compression of the sulphur trioxide, reduced to a simple annular border, so that in or of the gas containing it, is necessary in order the upper half of the drum there remains free to overcome the pressure head of molten sulphur; a wide central space by way of which the cham- (b) The discontinuity of the process with conbers are in communication with one another. sequent bad utilization of sulphur trioxide, which The drum 1 is passed through over its whole at the beginning is all reduced to sulphur dioxide, length by a shaft 10 emerging from the heads while growing portions thereof remain unaltered through stuffing boxes II and is supported in as the operation progresses, thus constituting a external bearings I2 of supports provided for this loss. purpose.

The disadvantages mentioned above are over- On the shaft I0 there are fitted a number of come now with the continuous process according perforated metal discs l3 conveniently arranged to the present invention for the refining of and spaced from one another in such a manner molten raw sulphur by means of sulphur trioxide, that the holes of two contiguous dis-cs are stagcharacterized in that gases containing sulphur gered. An external gearing serves to drive the trioxide and raw sulphur in molten condition are rotary shaft I 0 together with its perforated discs made to circulate in countercurrent flow rela- I3, by means of a drive motor not shown in the tionshi'p, said sulphur being provided in the form 3 drawings. of continuously renewed thin layers arranged in Two supports of different height, I15 and t6 planes substantially normal to the direction of respectively, keep the apparatus in a position ingas flow, clined with respect to the horizontal.

It is a further object of the invention to provide It is obvious that the number of internal chama device for carrying out said process, essentially bers, and consequently the length of the drum, constituted by a horizontal drum provided inside as well as the number of perforated discs, may with movable members suited to obtain the workvary in accordance with the cases of application ing conditions as required by said process. as well as with factors such as required output The invention will now be described in detail per hour, percentage of impurities in the raw with reference to the accompanying drawings, 40 material and so on. wherein one of the preferred embodiments of the The heating jacket 2 has the task of keeping invention is diagrammatically represented by the mass of sulphur in fluid condition, in particuway of example and t by way of limitation, as lar during possible interruptions of operation, foll w and it is limited to the lower half of the drum,

Fig. l is a longitudinal View, partly in section, because in e pper half there are al e dy 1101? of the apparatus according to the invention. gases circulating.

Fig. 2 is a transverse view, partly in section, The operation of the apparatus is self-evident. along the line 1-1 of Fig. 1, and Molten sulphur enters at 1 and leaves at 8 after Fig. 3 is a flow sheet of a plant for the purificasuccessively filling the various pockets existing tion of sulphur with the process according to the between the bafiles 9, while the gas containing invention, embodying an apparatus according to S0: enters at 5 and leaves at 6 after skimming Fig. 1. over the discs l3 and passing from one to the The apparatus in its essential lines is constiother mainly through their holes, which are contuted by a metal drum I, provided in its lower veniently staggered in the contiguous discs. The

discs turn with a good part of their surface immersed in the molten sulphur, leaving it coated with a thin film of molten sulphur, which thus is continually renewed and comes in intimate contact with the gaseous current containing 803, which as said passes in the contrary direction through the upper portion of the drum. Thus the countercurrent principle is applied in the apparatus in such a manner that sulphur progressively poorer and poorer of organic substances comes to contact a gas richer and richer of S03, which enhances the effectivity of purification.

The inclined position of the apparatus, together with its inner bafiles forming pockem for the fiuid mass, ensures that the latter, on advancing in the apparatus and, therefore, with the progress of purification, may not be contaminated again with the impurities present initially.

In Fig. 3 there is schematically diagrammed the layout of a plant for the refining of sulphur with the process and apparatus according to the invention. Raw sulphur is melted at 3| and is conveyed by a pump to the measuring device 32, which drops it into the apparatus 33 operated as described hereinbefore. After refining, sulphur passes into the vessel 34, where a filtering aid is added if needed, and then it is filtered in the filter 35. The filtered sulphur leaving at 36 is then solidified according to need, or even conveyed to combustion in a plant for the manufacture of sulphuric acid. If this is a contact process plant, the apparatus hereinbefore described finds special and. advantageous application, since the pressure drop existing after and before the catalysis chamber may be utilized for the circulation of the gas containing S03.

Of course, an embodiment of the apparatus in practice may comprise variants and modifications without departing from the scope of the invention.

Having now described our invention, what we claim is:

In a process for refining fused raw sulphur by means of sulphur trioxide, the step which comprises passing continuously by gravity molten raw sulphur in countercurrent flow relationship with gases containing sulphur trioxide and contacting said gases with said molten sulphur in a succession of thin layers, provided in planes substantially normal to the gas flow, continuously renewing said thin sulphur layers, and collecting and drawing off the molten sulphur thus treated.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 847,869 White Mar. 19, 1907 1,031,160 Bailey July 2, 1912 1,967,874 Dunn July 24, 1934 2,353,959 Hills July 18, 1944 2,424,336 Sieron July 22, 1947 2,433,552 Haney et a1 Dec. 30, 1947 2,554,109 Langhurst May 22, 1951 2,626,889 Carney Jan. 27, 1953 FOREIGN PATENTS Number Country Date 314,697 Great Britain July 4, 1929 350,574 Great Britain June 15, 1931 385,352 Great Britain Dec. 29, 1932 637,528 Germany Oct. 30, 1936 

